As the some heat wave continues to roll on, we continue to feature How Tos on making good quality iced coffee in the home. Our last How To talked about ice dripper coffee makers but with an average price over $200 for the brewing units, they can be a bit steep. How does under $30 sound? And the last article featured brewers that can take over five hours to brew coffee. How would you like a brewing time of under 90 seconds?
The answer is using an Aeropress to brew coffee you'll drink cold. We first wrote about using the Aeropresso for doing a cold coffee back in 2008, but that information is buried in an opinion article, and this method is so good, we figured it would be best suited for its own how-to. It also gives us a chance to update some information about using an Aeropress for cold brew.
The Aeropress for brewing coffee served cold
A lot of people who like specialty coffee already own an Aeropress, but if you don't you can pick one up on Amazon for under $26. It's a great brewer, and works just fine with the included paper filters. However, if you want the best tasting cups possible from the Aeropress, consider using aftermarket steel filters like the Coava ($15) or the Kaffeologie K250 filter ($10).
The Aeropress does well as a travel brewer for doing individual cups - it can brew up to 200-250ml of coffee if you max it out and you can really experiment with the brews to get different results. One of its best features is how fast it can be at brewing coffee: most of the brews we've done in the Lab or at home take only 60-75 seconds of steep time. We're going to tweak those times just a bit for our cold brewing method.
Even though this tutorial is for brewing a cold cup of coffee, we're starting off traditionally: that is, using hot water to create our elixir extraction. We'll also be doing a brewing method with the Aeropress that isn't in the product's manual, but has proven to be one of the best ways to brew with this device: the inverted brewing method.
Where things change are in the brew times, the brew volumes, and the amount of ground coffee we use.
Amount of Coffee: for a traditional Aeropress brew, we throw out the product's manual and go with 15 to 17.5g of coffee (based on 8g coffee for 100ml (g) water) depending on a variety of factors. But for this cold brewing style, we're going to up that volume - starting at 30g, and going up, depending on how much brewing water we'll be using. Our iced brewing ratio is 20g of coffee to 100g (ml) of water used. Since the Aeropress can hold up to around 230g (ml) of brewing water (once coffee is loaded) or more, we can use up to 40+g of coffee.
Type of Grind: If using the paper filters, use a grind that is only slightly finer than a standard drip grind. If using a metal filter, stick with a drip grind or slightly coarser.
Brewing Volumes: For a traditional Aeropress brew, we typically use about 225g (ml) of hot water for our 17.5g dose of coffee (ratio of 8g coffee/100g water). But when brewing for coffee served cold, you want to create more of a coffee concentrate. That means using less water (and agitating more - see below). For this demonstration and our 30g of ground coffee, we'll be using about 150g (ml) of water that is at least 200F or higher.
Brewing Times: In a traditional Aeropress brew, the steep (dwell) time is around 50-75 seconds with very little agitation at the beginning of the process. For our cold coffee brew, we're going with a 60 second agitation session + 30 second steep session to fully extract from the increased volume of ground coffee. The goal is to extract a more viscous, dense concentrated liquid from the brew. You really have to play around with this though, because it is quite easy to over-extract and deliver an excessively bitter brew.
These are the main elements in making a nice cup of cold coffee with your Aeropress. Of course, you'll need ice (use only fresh, filtered water ice), a sweetener if you like, and milk or cream (again, if you prefer). We like using cream milk (half and half, or 10% fat content) because it provides its own sweetness to the beverage eliminating the need for sugar or other sweeteners.
Why would you sweeten any cup of coffee? Well, we're dealing with a cold cup here, and the colder a beverage (or food item) gets, the more difficult it is for your tastebuds to perceive any tangible sweets that are in the coffee elixir. At the same time, the colder a beverage gets, the more (many) people notice bitters in the drink. We recommend adding minimal amounts of a sweetener (sugar, fructose, agave syrup, even small amounts of maple syrup!) to bring balance back to the cup and not to actually "sweeten" it into a sweet drink. Think fractions of a teaspoon instead of multiple tablespoons of sugar.
The inverted brewing method
If you do any kind of Internet research or reading about the Aeropress, you've no doubt come upon this term - inverted brewing. For many, it is the best way to make a cup of Aeropress coffee because you're creating a full immersion brew, but not losing any weak, under extracted liquid to the cup by brewing with the unit the way described in its product manual.
A serious caveat about the inverted brewing method is needed: it can be dangerous. You're dealing with hot, scalding water, and the effort to flip brewer + cup before plunging can result in the plunger becoming dislodged and hot coffee and grounds spraying everywhere. You must take absolute care when using this method and you do so at your own risk.
The pictures below detail the inverted brewing method. You can use this same method for traditional Aeropress brewing when using less ground coffee and more water. What we didn't photograph is the actual inversion (flip); we did this by first putting the glass (full of ice) upside down onto the Aeropress, and firmly and securely flipping the entire assembly - Aeropress and glass with ice - right side up to begin the plunging process. For hot coffees, you'd simply put an empty mug upside down on top of the inverted Aeropress, and flip it all.
Aeropress Cold Coffee Step By Step
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| What You'll Need |
For making a cold brew you'll need the aeropress, a filter (we prefer metal ones), a strong glass, fresh ground coffee and hot water. Milk and/or a sweetener are optional.
| Inverted Method |
Pioneered in CoffeeGeek's own forums, this has proven to be the best way to use the Aeropress for the best brews possible. You partially assemble the device, sticking the plunger in about 1cm (or more), and rest it on its plunger side.
| Adding the Coffee |
For a cold brew with the Aeropress, go 1.5x-2x the volume of ground coffee you'd normally use for a hot brew. In this example, we're using 30g of coffee for 150g (ml) of water. That's a ratio of 20g per 100ml.
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| A Lot of Coffee |
This is almost double the amount of coffee we'd normally put in an Aeropress. The idea is to make a coffee concentrate.
| Adding Hot Water |
This water is just off the boil and in an insulated container. It is around 95C (over 200F). We're adding about 150g (ml) of water.
| Stir it Up! |
Stir the slurry quite vigorously for the first 30 seconds or so. Then continue doing one or two stirs every 5-10 seconds letting the coffee steep and extract for up to 60 seconds.
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| Add the Filter |
Add the filter after about a minute (or more) of steep time. How much steep time? Depends on your coffee and your taste. Experiment!
| Adding the Ice |
As the coffee continues to steep for another 30 seconds or so, add your ice to your glass to fill it up. Make sure your glass is STRONG. It's going to bear a lot of weight soon. We like using big chunks of ice for this method. Once the glass is filled, place it upside down on the Aeropress and VERY CAREFULLY flip everything over.
| Plunge! |
Once you've flipped the Aeropress and cup, start plunging. Be careful though - it is VERY easy to send things flying. there is more resistance to plunging because of the greater volume of ground coffee used. Exercise extreme caution.
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| Finished Plunging |
Once you've finished plunging, keep a bit of the airspace between coffee and the plunger - this way, you keep the bloom out of the cup, which can lead to more bitters.
| Adding Milk |
This is optional, but we find the sweetness from half and half (10% fat) milk really gives a boost to the cup We don't add to much, but you can do it to taste. If you prefer, add a sweetener instead to balance the taste.
| Stir and serve |
Stir the brewed coffee until you start seeing condensation on the glass, and serve. Quite tasty!
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